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boost/cut capability. At 6dB the green LED will illuminate, and at 12dB the yellow LED will illuminate. 

 

4. BYPASS SWITCH & CLIP INDICATOR LED

 

Bypass Switch: 

When the red LED is illuminated, this indicates that the unit or channel is in 

the bypass mode. Signal is routed directly from the input to the output without passing through 

any circuit (often referred to as ”hard-wire bypass”). Use this switch to compare equalized and 

unequalized material, or to bypass the EQ section in the event of power loss or unit failure.  

 

Clip Indicator: 

- This red LED illuminates if any section of the equalizer is within 5dB of clip-

ping. Occasional flickering of this LED is acceptable, but if it remains on more than intermit-

tently you should turn down either the equalizer’s level controls or reduce the output level of 

the preceding component to avoid audible distortion. 

 

5. HI PASS FILTER (LOW-CUT FREQUENCY CONTROL)

 

To cut down on unwanted low frequency signals, this control determines the roll-off frequency of the 

High-Pass Filter (HPF). The roll-off frequency can be adjusted from 10Hz to 250Hz by turning this 

knob. Because of its high roll-off slope, the HPF can be efficiently used to cut down the ”HUM” noise 

from preceding instruments, or to reduce low frequency resonances, when speakers are installed in 

an enclosed acoustic environment. 

 

6. LOW PASS FILTER (HIGH-CUT FREQUENCY CONTROL)

 

To cut down on unwanted high frequency signals, this control determines the roll-off frequency of the 

Low-Pass Filter (LPF). The roll-off frequency can be adjusted from 3kHz to 40kHz by turning the 

knob. Because of its high roll-off slope, the LPF can be effectively used to cut down the high fre-

quency noise from preceding instruments, or roll-off excessive high frequency sounds to obtain a 

more natural sound in some acoustic situations. 

 

7. LEVEL CONTROL

 

This controls the level of signal coming into the equalizer. Turn this control down if the Clip LED 

illuminates steadily (meaning too strong an input signal). Unity gain can be set by turning this knob to 

the center detent position. 

 

Signal levels should be kept normalized through the equalizer. That is, the signal level, when by-

passed, should be the same (or a little lower) than when active. The reason for this is if the equalizer 

 

6

Summary of Contents for HQ 231

Page 1: ...HQ 231 DUAL CHANNEL 31 BAND 1 3 OCTAVE GRAPHIC EQUALIZER with FDC Feedback Detection Circuit USER S GUIDE ...

Page 2: ... Engineering instantly illumi nates the corresponding EQ band with the greatest signal That is if feedback occurs FDC identifies the band with the feedback frequency for quick correction During operation various LED s will illuminate as the signal passes The loudest band will correspond with the brightest LED When you hear feedback FDC and it s brightest LED shows you where to attenuate FDC confir...

Page 3: ...INSTALLATION These equalizers are designed for mounting in a standard 19 equipment rack or one of the many rack type portable cases available on the market The vertical height is 3 5 inches and depth is 7 5 inches POWER CONNECTORS This series of graphic equalizers have internal power supplies and are designed for operation from 120 or 240 volt 50 60Hz mains supply Power consumption is 30 watts In ...

Page 4: ...make sure all chassis are connected to earth ground either through the A C Power cord ground or by the front panel rack mount screws If the HQ equalizer is mounted in a grounded rack of equipment the ground to the case of the HQ may be lifted to prevent multiple ground paths which may cause a ground loop to occur OPERATING INSTRUCTIONS Before starting to equalize your sound system there is some in...

Page 5: ...ugh gain for your needs switch the range switch to the 12dB setting 10 If the Clip LED lights continuously turn down the level control until the LED is off most of the time FRONT PANEL CONTROLS 1 POWER SWITCH To turn the equalizer ON or OFF press the upper or lower portion of this button CAUTION Always turn on your equalizer BEFORE your power amplifiers are turned on and always turn off your equal...

Page 6: ...l off frequency can be adjusted from 10Hz to 250Hz by turning this knob Because of its high roll off slope the HPF can be efficiently used to cut down the HUM noise from preceding instruments or to reduce low frequency resonances when speakers are installed in an enclosed acoustic environment 6 LOW PASS FILTER HIGH CUT FREQUENCY CONTROL To cut down on unwanted high frequency signals this control d...

Page 7: ...el meter when adjusting the output level Control to aid in sending the proper level to your next piece of equipment REAR PANEL CONNECTORS CONTROLS 10 POWER CORD This cord is used connect the AC power source to your equalizer CAUTION Equipment for USA installation includes a captive power cord with a three pin polarized plug DO NOT REMOVE THE CENTER GROUNDING PIN 11 FUSE HOLDER This fuse holder con...

Page 8: ...eve Ground CAUTION Only one of these sockets can be chosen for audio connection at the same time XLR The XLR input connector is balanced and wired as Pin 2 Hi Pin 3 Lo and Pin 1 Ground CAUTION Only one of these sockets can be chosen for audio connection at the same time RCA PHONO The RCA Phono input is unbalanced at the tip Hi and the Sleeve Ground CAUTION Only one of these sockets can be chosen f...

Page 9: ...er is a solution to any number of sound problems or creative urges Typical reinforcement application of a two channel equalizer Equalization of a musical instrument Equalization of a guitar effects loop Equalizaton of audio signals from a mixer Mixer Instrument EQ EQ EQ EQ Speaker Speaker Mixer Send Return Amp PreAmp Stereo Effects loop Amp Amp Amp P Amp P Amp Guitar 9 ...

Page 10: ...ons This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs This warranty is void if the serial number is altered de faced or removed A R T reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufac tured A R T ...

Page 11: ...substitute The packing box is not rec ommended as a shipping carton Put the packaged unit in another box for shipping Print the RA number clearly on the outside of the shipping box Print your return shipping address on the outside of the box 5 Include with your unit a return shipping address we cannot ship to a P O Box a copy of your purchase receipt a daytime phone number and a description of the...

Page 12: ...pical 150 Ohms Maximum Level 22dBm 2k Ohms 18dBm 600 Ohms OVERALL GAIN RANGE Off to 6dB Unbalanced out Sliders Centered Off to 12dB Balanced out Sliders Centered RFI filters Yes Passive Bypass Switches Yes Overload LED Threshold 5 dB Below Clipping High Pass Filter 10 250Hz 12dB Oct Low Pass Filter 3k 40kHz 12dB Oct Frequency Response 20 20kHz 0 5dB THD Noise 01 20Hz 40kHz 10dBu IM Distortion SMPT...

Page 13: ...OLOGY 215 TREMONT STREET ROCHESTER NEW YORK 14608 USA 585 436 2720 Voice 585 436 3942 Fax www artproaudio com E mail cserve artproaudio com HQ 231 DUAL CHANNEL 31 BAND 1 3 OCTAVE GRAPHIC EQUALIZER with FDC HQ231 5004 100 13 ...

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